Hi, Jake 'The Cool Person' here.
You need to set the time on the PS2 to a few years into the future. To be on the safe
side, put it up 10 years (!!) when you have after when you have saved when the battle
starts and you turned the console off.
When you load, you get a cut-scene where Snake has found him, but he's dead. You also get
a humorous Codec. "Maybe...it was from old age." "You mean he kicked the bucket in the
middle of a battle?!"

you dont need to set the PS2 clock for ten years i just set it for seven days and it works